Expandable dowel

Abstract

An expandable dowel for insertion into a borehole comprising an expandable sleeve with one or more slots extending from one end thereof and expandable by at least one expanding member which engages the slotted sleeve, a screw-threaded bolt which is in screw-threaded engagement with the expanding member and has a shaft which is passed through a spacer sleeve adjacent the unslotted end of the expandable sleeve. The spacer sleeve is retained on the screw-threaded bolt by a bolt head or a nut screwed upon the screw-threaded bolt. The spacer sleeve, or a washer located between the spacer sleeve and said bolt head or nut is/are constructed so that it/they can be elastically or plastically deformed up to a predetermined amount by a force which acts axially of the bolt.

I claim: 
     
       1. An expandable dowel for insertion into a borehole, comprising: expandable sleeve means with at least one slot extending from one end thereof, at least one expanding member engaging said sleeve means at said one end for expansion thereof, spacer sleeve means adjacent that end of said expandable sleeve means which is opposite said one end and having an end face, a screw-threaded bolt in screw-threaded engagement with said expanding member and having a shaft which is passed through said spacer sleeve means and said expandable sleeve means, means on said screw-threaded bolt adjacent said spacer sleeve means for retaining said spacer sleeve means on said screw-threaded bolt, and washer means located between said spacer sleeve means and said means on said screw-threaded bolt, said washer means having a first substantially flat portion located outside the projection of a borehole into which the dowel is to be inserted and a second portion within the projection of the borehole, said second portion being provided with deformable sections bent outwardly with respect to the plane of said washer means and extending in a direction toward said spacer sleeve means, whereby upon tightening of said means on said screw-threaded bolt said sections first engage said end face of said spacer sleeve means and thereafter are deformed back into the plane of said washer means. 
     
     
       2. An expandable dowel according to claim 1, wherein said means on said screw-threaded bolt is a bolt head integrally connected to said bolt. 
     
     
       3. An expandable dowel according to claim 1, wherein said means on said screw-threaded bolt is a nut. 
     
     
       4. An expandable dowel according to claim 1, wherein said sections are elastically deformable. 
     
     
       5. An expandable dowel according to claim 1, wherein said sections are plastically deformable. 
     
     
       6. An expandable dowel according to claim 1, wherein said washer means is provided with a central aperture, and with slots extending from said central aperture, said sections being formed by material adjacent said slots bent out of the plane of said washer means. 
     
     
       7. An expandable dowel according to claim 6, wherein at least two slots are provided in equal angular distribution around said central aperture. 
     
     
       8. An expandable dowel according to claim 6, wherein at least three slots are provided in equal angular distribution around said central aperture.